Officials confirmed Sunday that the Winter Games were hit by a cyberattack during Friday’s opening ceremony, though they opted not to reveal the attackers.

“We know the cause of the problem but that kind of issues occurs frequently during the Games. We decided with the [International Olympics Committee] we are not going to reveal the source,” Pyeongchang organising committee spokesman Sung Baik-you told reporters, according to Reuters. “All issues were resolved and recovered [Saturday] morning.”

The attack crashed some of the Winter Games’ internal servers as well as the public Wi-Fi, South Korea’s Yonhap News Agency reported, which lead to some customers being unable to print out their tickets for the show.

Russia, a country not represented in the Winter Games due to doping concerns, predicted before the event that it would be blamed for a cyberattack on the festivities. “We know that Western media are planning pseudo-investigations on the theme of ‘Russian fingerprints’ in hacking attacks on information resources related to the hosting of the Winter Olympics Games in the Republic of Korea,” Russia’s foreign ministry said, according to Reuters.